There is a known semiconductor module including a chip-mounted board and a heat sink, as disclosed in, for example, FIGS. 1-4 of Japanese Laid-Open Patent Publication No. 11-330328. A surface of the chip-mounted board is in intimate contact with the heat sink via thermal grease. In the semiconductor module, the heat sink dissipates heat produced by the chip-mounted board. A resin-made or plastic enclosure case is directly bonded to the heat sink.